EVIDENCE FROM THE CASCADES 41 



seems faulty. The river cuts down faster in its narrowed section be- 

 cause it saws only at the bottom (but even then it does not excavate 

 deep basins), while the glacier cuts faster at the sides, and is prohibited 

 from rapid bottom cutting by every known factor and principle of 

 glacier mechanics. 



Ice erosion has been assumed as the cause of deep lake-basins which 

 lie in beds of former glaciers probably because it is the only near-by 

 agent on which suspicion can fall. It has left evidences of its presence 

 at the locality of the deed ; but the. circumstantial evidence is here mis- 

 leading. We probably have in these lakes a much larger and more diffi- 

 cult problem than has been supposed. The idea of glacial erosion must 

 certainly be abandoned, and the problem needs to be investigated along- 

 other lines. Following are a few suggestive facts which have a bearing 

 on the subject. 



If the deep Chelan basin were due to ice erosion, it would seem as if 

 lakes of similar character should be common in glaciated mountains. 

 There is apparently no good reason for attributing any exceptional char- 

 acter or power to the Chelan glacier. But lakes of the Chelan type are 

 strikingly wanting in glaciated areas. No lakes occur, so far as atlases 

 show, in the Caucasus, Pyrenees, Urals, or Carpathians, all of which moun- 

 tains held strong glaciers, and only a few are shown in the Himalaya, 

 mostly in the western districts, but no description of their character is 

 available. The Swiss and Italian lakes are most surely not produced by 

 ice erosion ; but the deeper ones, like Zug, 650 feet deep ; Geneva, 1,100 

 feet deep, and Maggiore, 2,600 feet in depth (the bottom 1,900 feet below 

 ocean), seem to belong in the Chelan category. The Dead sea, with its 

 surface 1,300 feet below sealevel, or Assat, east of Abyssinia and far below 

 sea, are types of basins which require explanation as truly as Chelan, but 

 no one has yet ventured to suggest ice erosion. If orographic or subter- 

 ranean movements or local subsidence can reasonably be invoked for 

 these basins, possibly even so narrow a basin as Chelan may have simi- 

 lar origin. 



The comparative absence of lakes in non-glacial regions is often over- 

 emphasized. An inspection of a good atlas will show numerous lakes 

 scattered the whole length of the American cordillera from Colorado to 

 Chile ; also in other non-glaciated mountain districts. It is probable that 

 many of these intermontane lakes can be explained only by earth move- 

 ments. An exhaustive investigation of the subject will possibly find 

 that Chelan, Maggiore, and Dead sea belong in the same type. 



Alaska. — There have been references to the glacial origin of valleys 

 and fiords in Alaska, and statements to that effect; but, so far as the 

 writer has found, no argument has been made nor proofs offered, except 



